A Thermodynamic Model for the Emergence of Natural Selection in Prebiotic Reaction Networks

TL;DR

This work introduces a Thermodynamic Abiogenesis Likelihood Model (TALM) that reframes abiogenesis as a persistence problem: prebiotic reaction networks persist when environmental energy input, internal energy storage, and structural resilience are thermodynamically aligned. A central persistence criterion, $y'(t)=y(t)+R_n-\Phi(t)\ge 0$, augments the basic energy balance $y(t)=z(t)+S(t)+\sum_i r_i-\sum_i x_i$ with an entropic–diffusive penalty $\Phi(t)$ and a resilience term $R_n$, integrating open-system thermodynamics with spatial organization. The model provides a probabilistic framework for comparing planetary environments and chemical ensembles, predicting when entropy-driven exploration can yield persistent, non-replicative chemical structures and how such persistence could seed later Darwinian processes. By offering testable scenarios across amphiphile self-assembly, surface effects, folding, and compartmentalization, TALM aims to bridge prebiotic chemistry with non-equilibrium thermodynamics and broader origin-of-life inquiries, potentially reframing the origin of life as a thermodynamic selection phenomenon rather than a uniquely replicated event.

Abstract

The origin of life is often approached through the lens of replication, heredity, or molecular specificity. This paper proposes a thermodynamic framework in which the emergence of life is driven by the persistence of reaction pathways that align energetically with fluctuating environmental inputs. We define a reaction viability inequality based on energy input, release, resilience, and expenditure, which selects for persistent chemical configurations without invoking heredity or genetic encoding. We further incorporate entropic dynamics and spatial constraints into an augmented persistence function, showing that systems far from equilibrium can simultaneously increase global entropy while supporting localized chemical order. These refinements lead to the development of the Thermodynamic Abiogenesis Likelihood Model (TALM), a probabilistic extension that estimates the likelihood of persistence-driven selection under diverse prebiotic and planetary scenarios. This framework redefines the conditions under which life-like organization may emerge and provides a testable, general theory for abiogenesis grounded in physical law.

Figures (5)

• Figure 1: Figure \ref{['fig:flowchart']} illustrates the logic of the reaction chain model under fluctuating environmental energy. The flowchart summarizes the operational logic of the reaction-chain persistence model under fluctuating environmental energy.
• Figure 2: Phase boundary between persistence and collapse predicted by the framework. The heatmap shows the fraction of simulated trials in which $y'(t)\geq0$ across multiple environmental intervals, plotted against the mean environmental energy input $\bar{z}$ and its variability $\sigma_z$. Higher $\bar{z}$ and lower variability favour persistence, demonstrating a clear transition between viable and non-viable regimes.
• Figure 3: Augmented persistence boundary including the entropic-diffusive penalty $\Phi(t) = \alpha / \Delta S_{\text{net}} + \beta D$. The heatmap shows the fraction of trials with $y'(t)\geq 0$ across intervals as a function of mean environmental input $\bar{z}$ and diffusion coefficient $D$ at fixed variability $\sigma_z$. Increasing $D$ raises the penalty and shifts the boundary to higher $\bar{z}$, illustrating how spatial dispersion can suppress persistence even under the same mean input.
• Figure 4: The energy–time plot illustrates how environmental energy input and internal energy storage jointly determine the viability of a reaction sequence across fluctuating conditions.
• Figure 5: Simulated thermal cycling and entropy export in early Earth conditions. The solid curve represents energy input $z(t)$ over a 48-hour period, modeled as a sinusoidal day-night cycle with baseline energy. The dashed curve shows entropy exported to the environment, $\Delta S_{env}(t)$, phase-shifted to reflect thermal dissipation lag. The shaded region indicates the viable persistence zone, where energy input exceeds the threshold required for reaction continuity. This illustrates how persistent systems must not only align with fluctuating $z(t)$, but also export sufficient entropy to remain thermodynamically viable.